This invention generally relates to cathode ray tubes and, more particularly, to a split foot damper for reducing vibrational energy in a tension mask of a cathode ray tube.
A color picture tube includes an electron gun for forming and directing three electron beams to a screen of the tube. The screen is located on the inner surface of the faceplate of the tube and comprises an array of elements of three different color-emitting phosphors. An aperture mask is interposed between the gun and the screen to permit each electron beam to strike only the phosphor elements associated with that beam. The aperture mask is a thin sheet of metal, such as alloy steel, that is contoured to somewhat parallel the inner surface of the tube faceplate. The aperture mask may be either formed or tensioned.
The aperture mask is subject to vibration from external sources (e.g., speakers near the tube). Such vibration varies the positioning of the apertures through which the electron beam passes, resulting in visible display fluctuations. Ideally, these vibrations need to be eliminated or, at least, mitigated to produce a commercially viable television picture tube.
The present invention provides a split foot damper for reducing vibrational energy in a tension mask having a border. The apparatus controls vibrations of the mask within the cathode ray tube that causes misregistration of the electron beam to the phosphor stripes on the screen. The need to damp these vibrations is essential to the correct operation of the cathode ray tube.
More specifically, the split foot damper has a first element having a first portion in moveable contact with a surface of the border and a second portion in moveable contact with the edge of the border, and a second element having a third portion in moveable contact with the surface of the border and a fourth portion in moveable contact with the edge of the border, where the two elements are connected to each other at a point that is affixed to the surface of the border. As the mask vibrates, the vibrational energy is transferred to the apparatus, wherein vibrational energy is dissipated as the apparatus rubs against the surface and edge of the border.